Emulsion aggregation toners are used in forming print and/or xerographic images. Emulsion aggregation techniques typically involve the formation of an emulsion latex of the resin particles, which particles have a small size of from, for example, about 5 to about 500 nanometers in diameter, by heating the resin, optionally with solvent if needed, in water, or by making a latex in water using an emulsion polymerization. A colorant dispersion, for example of a pigment dispersed in water, optionally also with additional resin, is separately formed. The colorant dispersion is added to the emulsion latex mixture, and an aggregating agent or complexing agent is then added to form aggregated toner particles. The aggregated toner particles are heated to enable coalescence/fusing, thereby achieving aggregated, fused toner particles. United States patents describing emulsion aggregation toners include, for example, U.S. Pat. Nos. 5,370,963, 5,418,108, 5,290,654, 5,278,020, 5,308,734, 5,344,738, 5,403,693, 5,364,729, 5,346,797, 5,348,832, 5,405,728, 5,366,841, 5,496,676, 5,527,658, 5,585,215, 5,650,255, 5,650,256, 5,501,935, 5,723,253, 5,744,520, 5,763,133, 5,766,818, 5,747,215, 5,827,633, 5,853,944, 5,804,349, 5,840,462, and 5,869,215.
Illustrated herein in embodiments are toner processes, and more specifically, emulsion aggregation and coalescence processes. More specifically, disclosed in embodiments are methods for the preparation of toner compositions by a chemical process, such as emulsion aggregation, wherein biodegradable semicrystalline polyester resin and mixtures thereof, are aggregated with a wax and a colorant, in the presence of a coagulant such as a polymetal halide or other monovalent or divalent metal coagulants, and thereafter stabilizing the aggregates and coalescing or fusing the aggregates such as by heating the mixture above the resin Tg to provide toner size particles.
Two main types of emulsion aggregation toners are known in the art. The first main type of emulsion aggregaton toner uses/forms acrylate based, such as styrene acrylate, toner particles. See, for example, U.S. Pat. No. 6,120,967.
The second main type of emulsion aggregation toner/process uses/forms polyester, such as sulfonated polyester toner particles. See, for example, U.S. Pat. No. 5,916,725. Examples of sulfonated polyester toner particles include poly(1,2-propylene-sodio 5-sulfoisophthalate), poly(neopentylene-sodio 5-sulfoisophthalate), poly(diethylene-sodio 5-sulfoisophthalate), copoly(1,2-propylene-sodio 5-sulfoisophthalate)-copoly-(1,2-propylene-terephthalate-phthalate), copoly(1,2-propylene-diethylene-sodio 5-sulfoisophthalate)-copoly-(1,2-propylene-diethylene-terephthalate-phthalate), copoly(ethylene-neopentylene-sodio 5-sulfoisophthalate)-copoly-(ethylene-neopentylene-terephthalate-phthalate), and copoly(propoxylated bisphenol A)-copoly-(propoxylated bisphenol A-sodio 5-sulfoisophthalate).
Conventionally, polyesters in toners are derived from bisphenol A, which is a known carcinogen/endocrine disrupter. It is highly likely that greater public restrictions on use of this chemical will be put into place in the future. Thus, alternative non-bisphenol A polyesters are needed. The disclosed biodegradable resins may very well be suitable replacements.
Several forms of these biodegradable resins are available commercially, and are made first as submicron aqueous emulsions. For most applications, the emulsions are subsequently dried before end use. However, for emulsion aggregation applications, the emulsions are particularly useful because the costly polyester resin emulsification step is elimination.